Chronic encephalopathies induced by mercury or lead: aspects of underlying cellular and molecular mechanisms.

Long term exposure to low doses of mercury or lead can induce neurasthenic symptoms with slight cognitive deficits, lability, fatigue, decreased stress tolerance, and decreased simultaneous capacity. After exposure to higher concentrations permanent neuropsychological deficits can be seen. The present paper gives a new idea of possible molecular mechanisms underlying the symptoms. Impairments of astrocyte function are probably important, especially due to their capacity to regulate the ionic and amino acid concentration in the extracellular micromilieu, brain energy metabolism, and cell volume. Recent results have shown that these functions are under monoaminergic control. Aspects of therapy are outlined.